This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background: Many microorganisms produce low-molecular-weight, iron(III) specific binding compounds called siderophores to compete for iron. Microbes are thought to produce unique siderophore structures to successfully compete for iron against other organisms in their environment. The siderophores isolated from terrestrial bacteria and fungi and from marine bacteria show promise as biomedical agents and for control of microbial growth. The siderophores produced by marine fungi have not been characterized and thus provide an unexplored source of novel bioactive compounds. Hypothesis: Marine-derived fungi produce siderophores with novel structures. Methods: Marine-derived fungal strains are screened for production of siderophores in pure cultures under conditions of iron limitation. Siderophores are isolated and structurally characterized using amino acid analysis, fatty acid analysis, NMR, mass spectrometry, and other techniques, as appropriate. Results and future directions: Twelve marine fungal strains have been screened for siderophore production;eleven of the twelve were found to produce siderophores. Structural analysis of siderophores produced by three strains is currently underway. One secreted siderophore has been isolated from an Antarctic strain of Leucosporidium. One secreted hydroxamate siderophore and two cell-associated siderophores have been isolated from Sporidiobolus salmonicolor 05-001. One secreted siderophore was isolated from Penicillium raistrickii ATCC42470. Mass spectrometric analysis of these siderophores has been completed. Current work focuses on purification of sufficient material to complete the NMR analyses.